Plc ladder logic question

Hey guys would really appreciate somebody helping me out with the answer for this question regarding ladder logic, I'm very new to Plc logic.

Thanks

Southmansouth said:

Hey guys would really appreciate somebody helping me out with the answer for this question regarding ladder logic, I'm very new to Plc logic.

Thanks

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Hey Dear

You use I0.0 (XIC- Examine if Close) When u press this switch from hardware then it is Examine for Close Condition.
And Other I0.1 (XIO- Examine if Open) Ehen u press this switch prom Harware then it is examine for open condition.

If you connected NO type Switch Then it give bit 1 for Press Condition & 0 For Release Condition. So for I0.0 (XIC) it passes the voltage when u press hardware Switch NO. And for I0.1 it Passes the Voltage when u release the switch.

XIC- When u give 0(Release) then it block the Supply And give Bit 1 (Press) then It passes the Supply.
XIO- When U give bit 0 (Release) then it Passes the Supply And Give bit 1 (Press) then it Block the Supply.

Southmansouth said:

Hey guys would really appreciate somebody helping me out with the answer for this question regarding ladder logic, I'm very new to Plc logic.

Thanks

Click to expand...

In your Image If Hardware Switch is NO type then you press only I0.0
And For off Condition u just press Both Switch. I0.0 Pass But I0.1 Block the Supply.
Becase XIO Convert the bit 1 to 0.

Hello and welcome to the forum.

Well this is obviously homework or a class project so I am more than happy to help but cant just give you the answer. I will do you better than that though.
I will share with you the secret to it all and you will be the smartest in your class tomorrow.

In PLC ladder logic you read the rungs from left to right.

Your first input in the example above (I:0/0) is what we who use Allen Bradley call a XIC (Examine if Closed)

If Power is applied to the terminal of this input on your PLC then there will be a value of 1 in the data table of your PLC for this bit, since it is a XIC (Examine if Closed) then the Input is said to be TRUE if there is a 1 in its data table.

So when you see an XIC instruction like your I:0/0 on a rung you say to yourself:

What does this instruction do?
Answer: it goes and looks for a 1 in the data table.
If it sees a 1 then it is TRUE, if it sees a 0 (Zero) then it is False.

You will see that it is true or 1 by the instruction lighting up in some way on your screen.
So if an XIC goes and looks for a 1 and it sees a 1 then it is TRUE and logic passes to the next bit.
If it sees a 0 (zero) then it is FALSE and logic does not pass any further.

Now for the tricky part.
Your next instruction is a little different, it is still an input instruction but it is what we who use Allen Bradley refer to as an XIO (Examine If Open).

This instruction works just the opposite of the first one we talked about. It goes and looks for a 0 (ZERO) or for NO power to be applied at the terminal of the input of the PLC.
If there is NO power present then there is a 0 (Zero) in the bit box for this input in the data table.
Like I said the XIO (Like your I:0/1) is True if there is a 0 (zero) in the bit box. You will see the XIO like your I:0/1 light up as True on your screen if NO power is applied to the screw terminal of its input on the PLC.

With the XIO instruction you say to yourself:
What does this instruction do?
Answer: it goes and looks for a 0 (zero)
If it sees a 0 (zero) then it is True, if it sees a 1 then it is False.

This is directly opposite of the first instruction we talked about, so you have to watch what you are looking for or it will trip you up.

If the first instruction is TRUE then logic will pass to the next instruction.
If the second instruction is TRUE then logic will pass to the next instruction.
And so on.
(reading from left to right)

If all of your INPUTS preceding your OUTPUT are TRUE then your Output will be True and it will GO AND WRITE A 1(ONE) IN ITS BIT BOX and you will see the output on the PLC turn on. (as well as light up on your screen)

If all of the Inputs preceding your Output are NOT true (at least one are false) then your OUTPUT will be FALSE and it will GO AND WRITE A 0 (zero) in its bit box in the data table, and your output will not be active in your PLC or on your screen.

Now with this little lesson under your belt, what do you think will be the state of the output?

What will be the state of each input as described in your question?

Take it one at a time from left to right and say to yourself what does this do.

Now as a wise man said to me, Follow your Hart!

Write back if you get stuck or if you got it.

BCS

EDIT: When I proof read this I had to make some edits so if you read it before I finished then go back and read it again.
You will want to read this over and over again anyway until you are saying it in your sleep involuntarily. LOL

Well it looks like Southman ran off while I was typing the above out.

For those of you just starting out, if you like what you read above and want to learn more.

Check out Ron Beaufort PLC BOOTCAMP on the internet.

The information above came right out of his playbook. (although it was paraphrased from my head, Ron tells the tale much better)

Ron has many instructional videos out on Youtube, and teaches an intense 5 day course for PLC training in Charleston South Carolina.

Describe the operation of the rung when there is an input voltage signal present at the PLC terminals for input I0:0 and I0:1.

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Reading the above and using the standard definition for AND as meaning both inputs inclusive, then nothing will happen (no actions will be taken) when there is voltage at both input terminals at the same time.

If there is voltage present at different times for each input terminal, then that is a different story.

What he said:

Bering C Sparky said:

LOL

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sixstringz said:

What he said:

Click to expand...

LOL,

Yes, I know!
My post was long and winded and I probably did not do what Ron taught us justice in my attempt to explain this to Southman.

But....If you are just starting out, learning and building on these small principals will serve you well and take you far.

I had a "Relatively Good Idea of the Basics" when I went into the class.
When I came out I feel that I have a "Firm Grip" on what is going on and more importantly, learning exercises like this has made me much more confident working with Automation.


For those that were just starting out, these basic principals were a bit of climb for them to grasp and retain, but once they got this system fixed in there head, they were able move up that hill with a pep in there step.

Sounds funny but I watched it happen with my own two eyes, the man knows what he is doing and he has a unique ability of being able to convey that information to you in a way you can understand.

(Obviously, reading my ramblings you can tell I don't posses that same quality..YET, but I am working on it.
One rung at a time, step by step, I still have a Long Way to go but one day I will peer over the top rung of that ladder, and be able to see what's up there, this I know)

BCS

You got to much time on your hands BCS... Go burn down a boiler, lol

boneless said:

You got to much time on your hands BCS... Go burn down a boiler, lol

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Ah, Wise Guy.... you think I am on the Triumph or something.

Just seen this, must have missed it earlier.

No, boiler working good (at the moment) don't want to mess with that.

Would you settle for a smaller version, our Incinerator is a POS, so I would gladly melt that one down if you like.

See you in October,

BCS

Sorry, we don't make incinerators, but I can help you melt it down in October .